So I read the full leaked document, try to put myself in the shoes of someone wanting to develop for the system (something I might actually do someday) and here's what stood out to me. Nintendo is doing a really good work making it easy for third party to make game for it.
The documentation is very clear, very well organized and written. It's easy to understand what everything does and how it will works. (you should read it, it's very enlightning)
Knowing thoses are document from way back in 2015 (when the internet though the NX was still in an unclear state, ahah) you can clearly see everything was already close to final, well documented and well thought out even back then. That is no half baked system.
You can see an big emphasis on feature wanted by third parties, e-commerce solution, selling in game item, selling online service, selling adittionnal content, season pass, everything big budget third party seems to want to do nowaday on other platform. All of thoses were really difficult if not impossible on the Wii U for example. If third party couldn't sell their stuff, it didn't matter what the capabilities of the hardware was in the end.
Speaking of capabilities. Nintendo is also providing online features, matchmaking, communication tools, ranking, cloud data. A comprehensive and clear user profil and account system. Something third party needs for multiplayer games, and the creation of an online community and the business of a game as a service. Something, again, the Wii U never had.
They also provide system wide "Applet" which are operation system based "mini app" to do some type of action, like you would find in mobile OS. Basically coming on top of the game to manage users, to see online or offline web page, to purchase digital goods, etc… All of thoses can be easily implemented by the developpers, are well documented and even slightly customized to fit the visual identity of your game.
Everything about developping for the switch seems to be about making life easier for developpers, No feature are mandatory, they even got rid of needing digital manual. For their HD rumble they say they're prodiving tools to make good use of it, like tools that automaticly translate a sound file into HD rumble data.
The document clearly state that the Switch is first and foremost a gaming centric device, that everything built into it is there to serve that one purpose and that focus shine throught.
There's even 2 kind of devkits. A fully feature one (with direct input/output for remote control, and a lot of additionnal stuff) and a lighter one, much closer to a consumer device. I suspect the former is there to be much more affordable than past devkits, allowing smaller studio to get into the platform for a much smaller fee.
As I have often stated, hardware specs is only one small part of what a third party look for in a new platform. As a third party you are poised to work within the limit of what the platform provide, what the provider is willing to tell you about it, and hoping for everything you're given to work as intended, you cannot spend millions into something that doesn't work as you need to and that you have no control on.
You can search for horror stories from developpers that dealt with launch Wii U dev kits: buggy tools, japanese documentation, lack of feature, weird functionnality, lack of tools, lack of english support, funky architectures, etc… To what extend this is true is difficult to gauge, but one thing is clear from this Switch document: 2 years before launch, the developpement environnement, and everything a third party would want to sell a game on a platform smoothly seems to be light years ahead of anything the Wii U was at launch or ever was.
This is what matter, this is why the Switch is not the Wii U. This is Nintendo listening, we might not see it, we might feel like "if they listened they would have release a Nintendo PS4" but in reality this is what third party look for. This and…well.. sells, Wii U had neither.